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Diffstat (limited to 'ports/sysdeps/tile/start.S')
| -rw-r--r-- | ports/sysdeps/tile/start.S | 183 |
1 files changed, 183 insertions, 0 deletions
diff --git a/ports/sysdeps/tile/start.S b/ports/sysdeps/tile/start.S new file mode 100644 index 0000000000..999bb535ca --- /dev/null +++ b/ports/sysdeps/tile/start.S @@ -0,0 +1,183 @@ +/* Copyright (C) 2011 Free Software Foundation, Inc. + This file is part of the GNU C Library. + Contributed by Chris Metcalf <cmetcalf@tilera.com>, 2011. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + In addition to the permissions in the GNU Lesser General Public + License, the Free Software Foundation gives you unlimited + permission to link the compiled version of this file with other + programs, and to distribute those programs without any restriction + coming from the use of this file. (The GNU Lesser General Public + License restrictions do apply in other respects; for example, they + cover modification of the file, and distribution when not linked + into another program.) + + Note that people who make modified versions of this file are not + obligated to grant this special exception for their modified + versions; it is their choice whether to do so. The GNU Lesser + General Public License gives permission to release a modified + version without this exception; this exception also makes it + possible to release a modified version which carries forward this + exception. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library. If not, see + <http://www.gnu.org/licenses/>. */ + +/* This is the canonical entry point, usually the first thing in the text + segment. The ELF standard tells us that the stack is set up like this on + entry (the left side is the offset from "sp"), in units of + __SIZEOF_POINTER__ entries: + + +0 argc + +1 argv[0] + ... + +(argc+1) NULL + +(argc+2) envp[0] + ... + NULL + ... ElfInfo + + The ElfInfo is pairs of key/value long words following the envp + pointers and terminated by a zero-valued key. + + Although not mandated by the standard, it happens to be the case + that we store the actual argv and envp strings immediately after + the ElfInfo data on the stack. + + On entry r0 points to the shared library termination function, or 0 + if there isn't one. +*/ + +#include <features.h> +#include <sysdep.h> +#include <arch/abi.h> + + .text + .global _start + .type _start,@function + .align 8 +_start: + /* Linux starts us with sp pointing at the conventional Elf layout, + but we need to allow two "caller" words for our ABI convention. */ + { + /* Load argc (stored as a "long", equivalent to a pointer type). */ + LD_PTR r1, sp + + /* Save incoming 'sp', which points to the Elf argument block. */ + move r52, sp + } + + { + /* Allocate stack frame callee space for __libc_start_main. */ + ADDI_PTR r12, sp, -(2 * REGSIZE) + } + + { + /* Get our PC. */ + lnk r13 + + /* sp is not necessarily properly aligned on startup because + of the way ld.so pops off leading argv elements. So align it. */ + andi sp, r12, -8 + } +.Lmy_pc: + + { + /* Pass the address of the shared library termination function. */ + move r5, r0 + + /* Compute location where __libc_start_main's caller is supposed to + store its frame pointer. */ + ADDI_PTR r12, sp, REGSIZE + + /* Zero out callee space for return address. Unnecessary but free. + This is just paranoia to help backtracing not go awry. */ + ST sp, zero + } + { + /* Zero out our frame pointer for __libc_start_main. */ + ST r12, zero + + /* Zero out lr to make __libc_start_main the end of backtrace. */ + move lr, zero + + /* Compute a pointer to argv. envp will be determined + later in __libc_start_main. We set up the first argument + (the address of main) below. */ + ADDI_PTR r2, r52, __SIZEOF_POINTER__ + } + { + /* Pass the highest stack address to user code. */ + ADDI_PTR r6, sp, (2 * REGSIZE) + + /* Pass address of main() in r0, and of our own entry + points to .fini and .init in r3 and r4. */ +#ifdef __tilegx__ + moveli r0, hw2_last(main - .Lmy_pc) + } + { + moveli r3, hw2_last(__libc_csu_init - .Lmy_pc) + shl16insli r0, r0, hw1(main - .Lmy_pc) + } + { + shl16insli r3, r3, hw1(__libc_csu_init - .Lmy_pc) + shl16insli r0, r0, hw0(main - .Lmy_pc) + } + { + shl16insli r3, r3, hw0(__libc_csu_init - .Lmy_pc) + moveli r4, hw2_last(__libc_csu_fini - .Lmy_pc) + } + { + ADD_PTR r0, r0, r13 + shl16insli r4, r4, hw1(__libc_csu_fini - .Lmy_pc) + } + { + ADD_PTR r3, r3, r13 + shl16insli r4, r4, hw0(__libc_csu_fini - .Lmy_pc) + } + { + ADD_PTR r4, r4, r13 +#else + addli r0, r13, lo16(main - .Lmy_pc) + } + { + auli r0, r0, ha16(main - .Lmy_pc) + addli r3, r13, lo16(__libc_csu_init - .Lmy_pc) + } + { + auli r3, r3, ha16(__libc_csu_init - .Lmy_pc) + addli r4, r13, lo16(__libc_csu_fini - .Lmy_pc) + } + { + auli r4, r4, ha16(__libc_csu_fini - .Lmy_pc) + +#endif + + /* Call the user's main function, and exit with its value. + But let the libc call main. */ + j plt(__libc_start_main) + } + { + /* Tell backtracer to give up (_start has no caller). */ + info INFO_OP_CANNOT_BACKTRACE + } +.size _start, .-_start + +/* Define a symbol for the first piece of initialized data. */ + .data + .global __data_start + .align 8 +__data_start: + .long 0 + .weak data_start + data_start = __data_start |